Core Viewpoint - The communication industry in China has achieved a historic breakthrough with the successful launch of the first cross-operator traceable VoWiFi call between China Telecom and China Unicom in Shandong, addressing issues related to weak cellular network coverage indoors [1][18]. Summary by Sections VoWiFi Technology - VoWiFi (Voice over WiFi) allows users to make voice calls over WiFi networks, solving issues in areas with poor cellular coverage [8][9]. - Unlike VoLTE (Voice over LTE) and VoNR (Voice over New Radio), which rely on 4G and 5G networks respectively, VoWiFi operates independently of cellular signals, requiring only a WiFi connection [8][9]. Historical Context - The first end-to-end traceable VoWiFi call was successfully made by Shanghai Telecom on May 20, 2022 [4]. - VoWiFi services had not been officially launched in China due to regulatory challenges regarding traceability [9]. Technical Innovations - A dual-factor authentication system was developed to ensure reliable traceability and security for VoWiFi calls, achieving higher precision than VoLTE [10]. - The cross-operator traceable VoWiFi solution has been recognized by experts from the Ministry of Industry and Information Technology and the China Academy of Information and Communications Technology [10]. Market Implementation - Following the announcement of VoWiFi by China Telecom in 2022, pilot programs were initiated in five provinces in 2023 [11]. - Users in cities like Guangzhou and Shenzhen can now experience this service, provided their devices support it [14]. User Experience and Benefits - VoWiFi can enhance call quality in areas with weak cellular signals, providing clearer and more stable communication compared to traditional voice calls [17]. - The service is automatically activated when mobile signals are poor, ensuring seamless connectivity [18]. Industry Impact - The technology has been adopted by both major operators and is set to become an industry standard under the China Communications Standards Association (CCSA), promoting collaborative development across the sector [19]. - The implementation of this technology not only expands the user base for VoWiFi but also opens new communication pathways in remote areas and special scenarios [19][20].